Primary outcome
PTSD Symptom Severity
For the studies included in the meta-analyses, the earliest study was performed in 2014, while the most recent study was performed in 2023. The median sample size across the studies was 36 participants per study. The median of the mean participant age was 37 years (ranging from 29 to 50 years).
Post-intervention (weeks)
8 studies provided data for PTSD symptom severity and contributed 9 effect measures to the PTSD symptom severity meta-analysis. The forest plot for PTSD symptom severity is presented in Figure 2.
Figure 2: Meta-analysis of the effects of exercise on PTSD symptom severity.
The meta-analysis found no evidence of a difference in PTSD symptom severity reduction between exercise and comparison groups (SMD = -0.08, 95% CI -0.24 to 0.07). Low heterogeneity was found as suggested by the prediction interval which is only slightly wider than the confidence interval.
Subgroup Analyses and Meta-regressions
We explored whether heterogeneity could be potentially explained by differences in study-level characteristics using subgroup analyses and meta-regressions. The following characteristics were explored as sources of heterogeneity for the primary outcome, PTSD symptom severity:
Exercise intensity (moderate intensity or high intensity)
Specific exercise type (aerobic, anaerobic or mixed)
Exercise augmented by treatment as usual (TAU)/therapy (exercise only or exercise + therapy/TAU)
Intervention length (weeks)
Subgroup analysis by exercise intensity
The test for interaction found some evidence of a difference between studies with moderate intensity and those with high-intensity exercise (Figure 3). Visual inspection of the forest plot suggests that effect is larger in the high intensity exercise subgroup.
Figure 3: Sub-group analysis of the effects of exercise on PTSD symptom severity by exercise intensity
Subgroup analysis by specific exercise type
The test for interaction found no evidence of a difference in PTSD severity between aerobic, anaerobic, or mixed exercise groups (Figure 4).
Figure 4: Sub-group analysis of the effects of exercise on PTSD symptom severity by specific exercise type
Subgroup analysis by exercise alone or tau/therapy augmented by exercise.
The test for interaction found some evidence of a difference between exercise alone compared with those with exercise in addition to psychotherapy or TAU (Figure 5). Visual inspection of the forest plot suggests that effect is larger for studies with exercise alone.
Figure 5: Sub-group analysis of the effects of exercise on PTSD symptom severity by exercise alone or TAU/therapy augmented by exercise
Meta-regression by intervention length
Overall, there is no evidence that the intervention length affected the treatment effect (Figure 6). The meta-regression analysis yielded a coefficient of 0.02 (95% CI: -0.01, 0.05).). Intervention length ranged from 3 weeks to 20 weeks, with a mode and median of 8 weeks.
Figure 6: Meta-regression of the effects of exercise on PTSD symptom severity by intervention length
Heterogeneity explained by covariates
| Moderator | Category | \(\beta\) | 95% CI | 𝞽2 |
|---|---|---|---|---|
| Overall effect | - | -0.08 | -0.24 to 0.07 | 0 |
| Exercise intensity | - | - | - | - |
| Moderate | 0.04 | -0.17 to 0.25 | 0 | |
| High | -0.23 | -0.45 to 0 | 0 | |
| Exercise type | - | - | - | - |
| Aerobic | -0.16 | -0.43 to 0.1 | 0 | |
| Anaerobic | -0.52 | -1.13 to 0.1 | 0 | |
| Mixed | 0.01 | -0.19 to 0.21 | 0 | |
| Exercise augmentation | - | - | - | - |
| Exercise alone | -0.38 | -0.77 to 0.02 | 0 | |
| TAU/therapy + augmented | -0.03 | -0.2 to 0.14 | 0 | |
| Intervention length | per unit (Week) increase | 0.02 | -0.01 to 0.05 | 0 |
Sensitivity Analyses
We examine the robustness of the findings for the primary outcome by excluding studies with high risk of bias (Figure 7). 3 studies included in the meta-analyses were rated as low or some concerns. When restricting the analysis to studies with moderate or low risk of bias, the effect of exercise on PTSD symptoms severity was SMD = -0.06 (95% CI: -0.27 , 0.14). For reference, the main effect size for the primary outcome was SMD = -0.08 (95% CI: -0.24 , 0.07), so the results do not change substantially.
Figure 7: Meta-analysis of the effects of exercise on PTSD symptom severity when excluding studies with high risk of bias
Reporting bias
Visual inspection of the funnel plot of standard error Hedges’ g suggested possible publication bias in favour the of exercise group.
There was insufficient studies to test for small study effect. The forest plot below shows the meta-analysis results of the primary outcome, PTSD symptom severity, ordered by the precision of the studies is presented in Figure 8. The smaller studies showed larger effects favoring the exercise groups compared to the larger studies which cluster around the line of no effect.
Figure 8: Forest plot of the meta-analysis results of the primary outcome ordered by the precision of the studies
add PTSD severity SWiM when finalized
Risk of bias for the PTSD symptom severity
The results of the risk of bias assessment per domain and study for the primary outcome, PTSD symptom severity is presented below in Figure 9 of the Extended Data. Nine studies reported PTSD outcome data post-intervention. Two studies did not report PTSD outcome data (Crombie et al., 2021a; Greene & Petruzzello, 2022). Five of the nine studies had an overall high risk of bias, three had some concerns, and only one was had low risk of bias. High risk of bias was mainly due to deviations from intended intervention (D2)(Voorendonk et al., 2023; Whitworth et al., 2019a; Whitworth et al., 2019b), missing outcome data (D3)(Rosenbaum et al., 2015; Voorendonk et al., 2023; Whitworth et al., 2019a; Whitworth et al., 2019b), and selection of reported results (D5)(Voorendonk et al., 2023; Young-McCaughan et al., 2022).
Figure 9 Results of the risk of bias assessment per domain and overall for the PTSD severity outcome
